One‐pot synthesis of 2‐imino‐1,3,4‐thiadiazolines from acylhydrazides and isothiocyanates

A one‐pot synthesis of 2‐imino‐1,3,4‐thiadiazolines was successfully achieved under mild conditions. The developed synthesis involves Fe(Pc)‐catalyzed aerobic oxidation of acylhydrazides followed by P(NMe2)3‐mediated annulation of the in situ generated N‐acyldiazene with isothiocyanates. The present annulation showed broad substrate scope with good functional group tolerance, and was effective on gram scale. One‐pot reaction consisting of Fe(Pc)‐catalyzed aerobic oxidation of acylhydrazides and P(NMe2)3‐mediated annulation of the in‐situ generated N‐acyldiazenes with isothiocyanates was developed for the synthesis of 2‐imino‐1,3,4‐thiadiazolines. It is notable that the developed protocol showed broad substrate scope and could be easily scaled up.